package 接口多态综合案例;

public class Computer {
    public void poweron() {
        System.out.println("笔记本开机");
    }

    public void poweroff() {
        System.out.println("笔记本关机");
    }

    public void useUsb(USB usb) {
        usb.open();
        usb.close();
    }


}
